1. Field of the Invention
This invention relates to weighing scales and, more particularly, to household weighing scales in which significant misalignment of the scale components can occur without affect on the weighing accuracy.
2. Description of the Prior Art
Weighing scales of the relatively inexpensive household type normally include vertically spaced-apart base and platform members and a force transmitting means between the platform and the base for converting a total weight force applied to the platform into a force related to and thereby indicating the actual weight. In practice, the force transmitting means typically includes various levers cooperating with complementary bearing surfaces on the platform and base members. More particularly, the levers and the platform and base members are commonly provided with complementary V-shaped slots and knife edges which cooperate with the slots to provide the bearing surfaces and, at the same time, to establish predetermined moment arms for assuring that the applied weight is translated into a properly related weight indicating force.
In such prior art weighing systems, it is essential that the levers and base and platform members be accurately aligned with each other so that the mating elements will fit together properly without binding or otherwise distorting the moment arms established by the elements. If dimensional accuracy is not maintained within acceptable limits, the scale may not operate or, at the very least, the indicated weight may be outside of the acceptable range of accuracy. As a result, it is essential that all of the various elements be manufactured to relatively low tolerance ranges in order to assure that they will be aligned properly when the scale is assembled. The holding of fine tolerances on all parts, particularly large plastic base and platform members, in order to minimize tolerance build-ups tends to increase manufacturing complexity, waste, and cost. It would be ideal if accuracy could be maintained without requiring that tolerance build-ups remain small.